Systhesis and characterization of aluminium substituted nickel magnesium ferrite nanoparticles

Abstract

With excellent magnetic and electrical properties, ferrite magnetic nanoparticles have wide range of applications in wide range of fields. With tuneable physical and chemical properties, ferrites can have more applications and become more suitable for advancing technology. Normally, two approaches are used in tuning the physical properties of ferrites, first approach is changing the synthesis methods and the second approach is altering the types of cations being introduced into the ferrites. In this study, Aluminium substituted nickel magnesium ferrite with general formula Ni1-xMgxFe2-xAlxO4 were synthesised with co-precipitation method. Three annealing temperature were chosen at 600°C, 800°C and 1000°C. The samples were characterised using X-ray diffractometer (XRD) and Fourier Transform Infrared Red Spectroscopy (FTIR) for structural analysis. Field emission scanning electron microscope (FESEM) was used to analyse the morphological property of the samples. Energy dispersive X-ray spectrometer was used to study the composition of the samples. The dielectric properties of the samples were analysed by using impedance analyser. XRD and FTIR shows the single phase spinel structure of the samples. Crystallite size decreases with increasing ratio of aluminium and magnesium except for the samples annealed at 600°C, and increases when the annealing temperature increases. Lattice constant of samples annealed at 800°C and 1000 °C are almost constant but becomes smaller when annealed at 600°C, which may due to redistribution of the cations with different annealing temperature. The degree of crystallinity increases as the annealing temperature increase, when the ratio of aluminium and magnesium reach 0.8, the degree of crystallinity deteriorated. FESEM micrograph shows the homogeneous distribution of the nanoparticles. Increment of dielectric constant and low loss factor of this substituted ferrites make it a good candidate for high frequency device applications.